Description

The DUX4 gene is located within a D4Z4 repeat array in the subtelomeric region of chromosome 4q. The D4Z4 repeat is polymorphic in length; a similar D4Z4 repeat array has been identified on chromosome 10. DUX4 (also known as Double homeobox 4) is the leading candidate causative gene for facioscapulohumeral dystrophy (FSHD), a degenerative skeletal muscle disease and one of the most common muscular dystrophies. FSHD is caused by the deletion of a subset of D4Z4 macrosatellite repeats on chromosome 4. Each repeat contains a retrogene encoding the double-homeobox factor DUX4. DUX4 expression is epigenetically suppressed in differentiated tissues and the residual DUX4 transcripts are spliced to remove the carboxyterminal domain that has been associated with cell toxicity. In FSHD individuals, the expression of the full-length DUX4 transcript is not completely suppressed in skeletal muscle, and possibly other differentiated tissues, and results in a small percentage of cells expressing relatively abundant amounts of the full-length DUX4 mRNA and protein. [Snider et al. (2010) PLoS Genetics.6(10): e1001181]